Portable collimator apparatus fob



Oct. l2, 1948 s H. PETRY Erm. 2,451,409

rom-mm comxinon Prunus ron sulla m unoscors um or-ucn. :vsnl or msnm-s 5 Shoots-Shut 1 F1106. l'lb. 19, 1945 Oct. 12, 1948. s, H. PETRY ETAL 2,451,409

PORTABLE coLLIMATon APPARATUS Fon TESTING THE GYRoscoPE AND oP'ncAL sYs'rEu oF nomsmu'rs Fild Fb. 19, 1945 5 ShOOtEPShQOt 2 INVENTORS ,Stanton If Pecf;q lfartlamd .5'. Snag/ade Oct. 12, 1948. s. H, Pr-:TRY ETAL 2,451,409

PRTBLB COLLIHATUR PrArTUS FOR TESTING THE GYRQSCOPI AND OPTICAL SYSTEM OF BOMBSIGH'I'S Filod Fab. 19. 1945 5 Sheets-Shut 3 1/ :malin/f l AJ 2, .ha 4 l l r4 INVENTORS: .Stanton H .Pdrzg BY Hartland-S. Snyder @ed ttor-n.93.

2,451,409 R TESTING THB IGI-ITS 5 Shun-Sheet 4 Oct. l2, 1948. s. H. PETRY ETAL PDRTABLE COLLIIATOB APPARATUS F0 GYROSCOPE AND OPTICAL SYSTEM OF BOMBS rund Feb. 19. 1945 2 i.. m X 9 ow i m 6 i@ 5 CNW. 4 wf 6M o- ../L x l Y a O W Ww 3 m z a 8 9 z 5 2 a g 1 1, d J a 968 7 4 a F z at@ J@ 5' S3 56 JQ J6' Oct. 12, 1948. s. H. PETRY Erm. 2,451,409

PORTABLE COLLIIATOR APPARATUS FOR TESTING THE GYROSCOPE AND OPTICAL SYSTEM OF BOMBSIGHTS Filed Fab. 19, 1945 5 Sheets-Sheet 5 um en/ewa ne Mcm TOP HEAVY CVRD EQ' 9 1NVENToR3= Patented Oct. 1L 1948 2,451,409 LLIMATGR APPARATUS FOR PORTABLE C TESTING TBE GYRGSCOPE AND OPTICQL SYSTEMOEBQMBSIGBTS sumen n. rem. Evanston, ma umana s. sn,-

der, Chicago,

lll., assignors to Victor Adding Machine Co., Chicago, Ill., a corporation of Illinols Application February 19, 1945, Serial No. 578,174

'l Claims. l

This invention relates to a testing device for use in checking and adjusting the telescope and static balance ci a gym-stabilized bombsight.

Generally speaking, it is the purpose oi this invention to provide a bombsight testing instrument oi unusually compact form which includes a builtin collimator.

At the present time bombsight testing equipment, with which we are familiar, has certain definite disadvantages when considered from the standpoint or size, cost, accuracy and weight.

It may be further pointed out that as air bases are moved or advanced from one locality to another, transportation of heavy and bulky' bombsight test equipment becomes a serious and vital factor.

It is the broad purpose oi our invention to obviate the above-mentioned objections found in connection with present day testing equipment for gym-stabilized bombsights by providing improved test equipment which is readily portable, which weighs approximately ten pounds, and which is economical to manufacture, highly accurate in operation, and capable oi being used without removing the bombsight fromY the plane.

A further object is to provide novel testing equipment for a gym-stabilized bombsight which is removably supported by the sight-itself, an instrument capable of testing all the important functions of the sight, and one the size and weight of which permits it to be carried'by the plane and included as a part of the planes equipment.

A still further object of the present invention resides in the use of a colliliiatorv equipped with sensitive level bubbles, special mounting bracket, means for universally adjusting the position oi the collimator relative to the bracket, and a specially designed reticle within the oollimator.

More limited objects oi the invention are to provide an edicient and relatively simple testing instrument for gym-stabilized bombsights, composed in most part oi' simple elements that may be readily fabricated into a compact and sturdy structure possessing the features above pointed out and operating in a highly satisfactory man-1 ner.

The invention, associated with a gym-stabilized bombsight. is illustrated in the accompanying drawings, and while we shall proceed to describe the same in detail, it lwill be understood that the invention, in its broader aspect, is not limited to the structural details shown further than is required by the terms oi the appended claims.

In the drawings:

the test collimator, Fig. 4 being a plan view partly in horizontal section along the line l-l oi Fig. 5, and Fig. 6 a side elevation partly in vertical section along the line 6-8 o! Fig. 4. f

Fig. 7 is an enlarged diagrammatic view oi' the collimator reticle graphically showing the move- Ament oi the telescope cross hairs relative to the reticle during certain tests hereinafter fully explained.

Fig. 8 is a view similar to Fig. 'I showing the cross hairs oi the telescope in exact registry or at zero position relative to the principal axes of the grid and.

Fig. 9 is a highly magniiied view of the grid depicting typical readings at aproximately two minute intervals oi' a bombslght under varying conditions.

General description It is believed that the detailed description oi our improved test collimator for a gym-stabilized bombsiglit will be more readily understood if it is read with a general knowledge of the structure and functions performed by the sight and the general manner in which the objects of our invention are attained.

There is illustrated herein one form oi Syrostabilized bombsight with which our invention may be used. As shown. this sight consists generally of a housing i0 (Fig. l). within which a gyro i-I and a telescope I2 are housed tor pivotal movement within a cardan Il, the cardan in turn being pivotally mounted with respect to the hous- 48 ing I0 in the conventional manner. 'i The yro and telescope are connected to one another through a diiierential link Il (Fig. 2) in a manner and for reasons more fully explained hereinafter. and mirror ill of telescope I2 is moved by a cable 50 I8 and drum il the latter being driven by a computer shown generally by reference character Il. The lower haii of housing lll is provided with an opening or window 20 for the telescope mirror I5 and this opening is normally covered by a glass plate (not shown) fitted lwithin grooves ll in the side walls of said opening. It will be observed trom Fig. 3 that our improved test collimator is supported within this opening by the grooves 2I in a manner presently disclosed.

Generally speaking, the more important tests to be performed on the sight through the use of our novel test collimator are as follows:

l. The optical axis o! telescope I2 is brought parallel to the spin axis of the gyro I I.

2. The section o! the bombsight which is stabilized in azimuth is set parallel to the longitudinal cross hair of the telescope so that no movement of said cross hair is observed when introducing trail into the sight.

3. With a known value of trail and a dennite amount of drift angle introduced into the sight, observed movement of the cross hairs with respect to the collimator reticle should equal the trail times the sine oi the drift angle.

4. With the gyro running and uncaged, and the telescope cross hairs set to zero position relative to the collimator reticle, the direction and amount of travel of the cross hairs during a deilnite period of time in all four cardinal headings will indicate the precession of the gyro caused by earth's rotation, out of balance, faulty bearings, etc.

Test collimatr Referring now to a detailed description oi' our invention, and for the present to Fig. 3, the reference numeral 22 designates a bracket the upper end of which has a locating plate 23 secured thereto by screws 24. This plate is slidably received by the grooves 2| in housing I3, as best illustrated in Figs. 2 and 3, and in this manner the test collimator is removably attached to and supported by the lower half of the bombsight housing I3. The lower end of bracket 22 is provided `.with three arms 23, 26 and 21 (Figs. 3 and 4) drilled and threaded to receive the threaded ends of levelling or Jack screws 23, 23 and 33 respectively. The lower swivel ends 3i and 32 o! said screws 23 and 23 respectively engage level brackets 33 and 34 which extend outwardly from. and are secured to, the collimator housing 35 by screws 36, whereas the swivel end 31 of jack screw 33 engages a flat surface on the lamp housing 33 as clearly shown in Fig. 3. This lamp housing is preferably attached to the collimator housing by screws 33 shown in the plan view Fig. 4.

It will be observed from Figs. 3 to 6 that collimator housing 3S has a universal connection with bracket 22 through a pin and trunnion connection 43, and that spirit levels 4I and 42 are adiustably mounted upon level brackets 33 and 34 at right angles to one another, in any suitable manner, as for instance by studs 43 and lock nuts 44.

With further reference to lamp housing 33 (Fig. 3) it will be noted that a lamp socket 43 is mounted therein and carries a small electric lamp 43 the filament 41 or which is centrally disposed relative to the reticle 43. The reticle is preferably made from an opal diilusing glass and is provided with an etched grid 49 better shown in Figs. 6 to 9, the graduations oi' which represent mils. The reticle 48 is mounted within a ring or bezel Eiland the ring in turn is fastened within the collimator housing 35 by screws 3i in a manner clearly shown in Fig. 3.

A pair of irrors 32-33. angularly displaced relative to on another and to the reticle 43, are held over openings in the housing 33 by clips 34 and screws 33, there being resilient pads or 4 washers 33 between the mirrors and clips to cushion the mirrors against breakage.

Note is next to" be made of obiective lens 31 which is preferably in the form of an achroxnatic ydoublet composed of two elements 33 and Il cemented together in the conventional manner and made from a suitable optical glass ground with great precision. The lens elements 33-33 are of the same diameter and fit snugly within a retainer ring 33 'which is externally threaded and adiustably received by the threaded bore 3| in housing 33. The lens 31 is focused on reticle 43 in such a manner that a beam oi' light C is emitted from the collimator, the rays of which are parallel. After the lens 31 is properly iocused with respect to reticle 43. ring 33 can be locked by a convenient set screw 32 carried by the collimator housing. Next the beam of light C is brought` to a true vertical, in the usual and well known manner and then the levels 4I and 42 are adjusted by means of the studs 43 and lock nuts 44 until their bubbles" 34 assumes. neu-V tral position.

From the foregoing detailed description of our improved test collimator, it will be understood that the ilrst step towards checking the iunctions oi a gym-stabilized bombsight is to remove the Blass plate from window 23 and mount the collimator on the sight housing by sliding the plate 23 into the grooves 2i in the manner heretofore explained. After the collimator has thus been mounted upon the bombsight the next procedure is to adjust the levelling or jack screws 23. 23 and 33 by turning their hand wheels I3 until the bubbles 33 and 34 oi' spirit levels 4I and 42 respectively assume a neutral position, or the position shown in Fig. 4. This insures that a vertical column oi parallel light rays are emanating from the ccllimator within the field of view of the bombsight telescope i2.

Next the gyro II. is caged to bring its spin axis A-A to a true vertical position. This is accomplished by clamping the cardan I3 to the sight housing I3 by the use of removable and adjustable clamps 65 and by clamping the gyro il with respect to the cardan I3 by a similar clamp 33. Through proper adjustment of the clamp screws 31, the bubbles 38 and 33 of the gyro spirit levels 13 and 1I, are brought to a neutral position (as shown in Fig. i) and when in this position it is an indication that the spin axis A--A of gyro II is vertical. In the conventional manner the bombsight computer I3 is adjusted to a position which represents a zero sighting angle, and by observation of the grid 49 through the bombsight telescope I2, the telescope cross hairs l2 should coincide with the principal axes 13 of said grid 43 as illustrated in Fig. 8. If this condition does not exist it can be corrected in a fore and aft direction jby changing the length of cable I3 through adjustment of drum I1 thus moving the mirror I3; and in an athwartship direction by changing the angular displacement of lever 14 (Figs. 1 and 2) with respect to lever 13 through adjustment screw 13. Thus, the optical axis B-B, of the telescope I2 has been brought parallel to the spin axis A-A of gyro II and this constitutes the iirst major adjustment ot every bombsight.

Adjustment of the stabilized section ofthe sight so that movement of the trail arm 11 imparts no movement of the telescope cross hairsl assigns gun by insuring that the pointer Il (Fig. i) carrled by the sight is set at zerol over the scale 19, the latter being mounted upon the stabilizer I0. Thenthetrailarml'lismoved iasforexampie toilmilsasillustratedinl'imi) withrespect to its'scaleli. and ii this movement of the trail `erin produces any movement of tbeteleseope cross hairs I relative to the grid II, it is an indicstion tha the section of the sight stabilized in azimuth (indicated generally at l Fig. l) is` improperly adjusted. This can be corrected by rotating the stabilized section Il of the sight with respect to the stabilizer Oil. in a manner well known to those skilled in the art of gyra-stabilized bombsights. until no movement of the telescope cross hairs relative to the grid of the reticle is observed during movement of said trail arm.

Another test to be performed upon the bombsight. by the use of our novel test collimator, is a functional test which involves setting the trail arm Il at a known value, say 90 mils on the scale Il as shown in Fig. l. then placing a given amount of drift in the sight. An example would be to set the pointer 1l to 30 degrees on the scale 19. This is accomplished by manually turning the drift knob UI (clockwise for right drift and counterclockwise for left drift) which in turn, through means of worm U4 and toothed sector 85, rotates the sight with respect to the stabilizer 80. Then by observing the displacement of the telescope cross hairs 12 relative to the grid 49, such displacement should equal the trail times the sine of the drift angle, or 45 mils in the example given.

vand illustrated in Fig. 7.

The third major adjustment of the bombsight and the second functional test performed by the use of our invention will now be described in detail and relates to checking the performance of the gyra-telescope combination. First of all the sight is set with the fore and aft axis in one of the four cardinal headings, for instance north. with the gyro running at an approximatespeed of 8,000 R. P. M. and when this speed is attained the gyro should be uncsged; The cross hairs 12 of telescope Il should then be brought to zero position with respect to the principal axes il of the grid, as illustrated in the diagrammatic view Fig. 8. This is accomplished by simultaneously turning the manual levelling knobs 80 and l1 the first of which. through its roller Il. applies a torque to gyro ii thus causing the cardan i3 to rock within housing lil to bring the athwartship cross hair of the telescope into registry with the corresponding axis of the grid, and the second of which, through its roller B9, applies a torque to the cardan i3 thus causing the gyro ii to rock within cardan Il to bring the longitudinal cross hair of the telescope into registry with the corresponding axis of the grid.

When the telescope cross hairs are thus brought` into registry with the principal axes of the grid. a dennite period of time is permitted to elapse and the direction and amount of travel of the telescope cross hairs, with respect to the grid. represents the precesslon oi' the gyro due to the earth's rotation. This precession. or the precession of the gyro due to earths` rotation, is of a known value and in a generally easterly direction. Deviations from this known value represent a defective function of the gym-cardan combination which may be caused by imperfect bearings. l excessive bearing friction or an out of balance condition. These causes of deviations affect the precession differently in each of the four cardinal headings. By observing the direction and speed 6 of the movement of the telescope cross hairs with respect to the grid, in each of the four headings. one skilled in the art of bombsights is enabled to determine the cause of any deviation from the known value.' For' example. travel of the tele- -scope cross hairs across the grid is illustrated in Fig. 9, this movement being due to various causes of deviation such as a top or bottom heavy gyro. bad bearings. friction in tli'e bearings. or an out of'balance condition of the gyrocardan combination. Accordingly. by checking the bearings and .adjusting the gyro cardan balance until the precession maintains a predetermined value in all four headings constitutes the third adjustment and second functional test completed through the usel of our device.

While we have shown and described but a single 'embodiment of our invention, it will be apparent to Athose skilled in the art of bombsights that numerous changes may be made in the mechanical details thereof without departing from the principle of our invention. We, therefore, desire the scope of our protection 'to be limited only by the claims which follows:

We claim:

l. An instrument for testing and checking the telescope and static balance of a gym-stabilized bombsight comprising. in combination, a bracket having means for detachably securing lt to a fixed part of the bombsight; a collimator housing universally connected to said bracket; a pair of spirit levels carried by the housing and disposed at a right angle relative to one another' a plurality of levelling screws arranged to ad ust said housing relative to said bracket to bring the bubble oi said levels to a neutral position; a reticle mounted within said housing: a light source to one side of said reticle; and an objective lens positioned toA receive light from the reticle and foused upon said reticle whereby a vertical column of light having parallel rays is emitted from the collimator, said ray of light being vertical when said spirit levels are in neutral position and beingused in checking various positions of the bombsight telescope cross hairs with respect to said reticle, substantially as described and for the purposes set forth.

2. An instrument of the class described for checking and adjusting the telescope and static balance of bombsights comprising, in combination, a supporting bracket having means at one end thereof for removably and rigidly attaching it to the bombsight; a collimator housing univer sally connected to the other end of said bracket: levelling screws carried by the bracket; a pair of spirit levels mounted upon the housing, the bubbles of which are moved to a neutral position by adiustment of said levelling screws to bring said housing to a level position; an achromatic doublet objective lens and a reticle mounted within said collimator housing said reticle being positioned at the focal plane of the objective lens: and a light source unit mounted upon said housing adjacent one side of said reticle opposite to that of said objective lens: whereby. a vertical beam of light having parallel rays is emitted from the collimator housing. substantially as set forth and for the purposes specied.

3. An instrument of the character described for testing and adjusting the telescope and static balance of gym-stabilized bombsights comprising, in combination, a collimator housing having means for universally connecting it to a bombsight for support thereby. means to adjust the collimator housing universally, means for indi nate the reticle. and an objective lens rendering parallel the light rays emanating from the collimator thereby to provide a deiinite optical reference direction for the testing adjustment of the bombsight.

4. An instrument for facilitating the testing and adjustment of gyra-stabilizedbombsights and to determine when the optical axis of the` bogibsight telescope is parallel with the spin axis o1 the gyro comprising a collimator housing, a coliimator within said housing and comprising a retic1e. universally adjustable means to level and to secure the collimator housing to the bombsight to be tested, a light source illuminating the reticle, and an objective lens receiving light from the reticle, characterized by the fact that the collimator provides a vertical column of light rays usable as a definite reference direction in testing and adjusting the bombsight when the latter is fixed in a position such that the optical axis of its telescope is vertical. A

5. In a bombsight the combination of a rigi frame, a telescope mounted in the frame and having means for changing the direction of its optical axis with respect to the frame, a gyroscopc mounted in the frame and having a connection with the telescope operative to change the direction of its optical axis. and means for facilitating the adjustment of the optical airis oi the tele scope with respect to the spin axis of the gyroscope, to adjust the gyroscope and its connection with the telescope to a predetermined normal relationship comprising: a bracket having means for detachably securing it to the trame, a reticle housing, level indicating means on the housing, a universal joint connecting the housing to the bracket, means for universally adjusting and tlxing the position of the housing with respect to the bracket, an illuminated reticle in the housing, and a lens to project the light from the reticle in parallel rays toward the telescope.

6. An instrument for testing and checking the telescope and static balance of a gyra-stabilized bombsight comprising, in combination, a bracket having means for removably connecting said instrument to the bombsight: a collimator housing universally connected to said bracket: a pair of spirit levels carried by said housing; means to adjust said housing relative to-said bracket to bring the bubbles of said levels to a neutral posil neutral position.

t 8 tion; a reticle supported within said housing: a light source disposed adjacent Vone side oi' said reticle; and an objective lens supported within 'said housinglndinfocuswithslldreticletopruvide a vertical column of parallel light Il!! directed toward time neldod vision of said tele-- scope, and which aresparallel ina rayloi. light which passes along the optical axis of the tele scope when the latter is in static vertical position# and when the bubbles ci' 'said levels arein a '1. an insti-ment ci the character described for use in checking gyra-stabilized bombsight: comprising, in combination. a telescopic bombsight viewing means, a collimator housing bovini means for universally adjusting and securing it in a predetermined position relative to the bombsight; means for indicating when the collimator is in said predetermined position; 'a reticle mounted within the collimator housing; said reticle having a rectangular cross line grid, the graduation: oi which arespaced to represent mils in the bombsight to be checked; a light source unit adjacent the reticle; and an objective lens rendering parallel the light rays oi a vertical column ci' light emanating trom the collimator housing, the construction being such that movement of the bombsight telescope cross-hairs relative to said grid graduations is utilized to check and adlust the telescope and static balanceof the bombsight.

` STANTON H. PEI'RY.

HAR'I'LAND B. BNYDER.

REFERENCES CITED The following references 'are oi' record in the le of this patent:

UNITED STATES PATENTS Number Name `Date 862.293 Ewasey Aug. 6, 1997 1,434,209 Hort Oct. 31. 1922 1,449,527 Mackensen Mar. 27, 1923 1,524,788 Gardner Feb. 3, 1925 1,589,797 Eppenstein June 22,1926 1,628,776 Henderson T-- May 17, 1927 1.784.929 Estoppey Dec. 16, 1930 1.955.746 Inglis Apr; 24, 1934 2,129,130 Hammer Sept. 6. 1938 2,324,444 Wappler Apr. 13, 1943 2,364,152 Macgill Dec. 5, 1944 2,365,361 Street Deo.' 19, 1944 2,392,631 Harasta Aug'. 14, 1945 2,384,643 Schade Sept. 11, 1945 

